Adaptation of sensor morphology: an integrative view of perception from biologically inspired robotics perspective

Sensor morphology, the morphology of a sensing mechanism which plays a role of shaping the desired response from physical stimuli from surroundings to generate signals usable as sensory information, is one of the key common aspects of sensing processes. This paper presents a structured review of researches on bioinspired sensor morphology implemented in robotic systems, and discusses the fundamental design principles. Based on literature review, we propose two key arguments: first, owing to its synthetic nature, biologically inspired robotics approach is a unique and powerful methodology to understand the role of sensor morphology and how it can evolve and adapt to its task and environment. Second, a consideration of an integrative view of perception by looking into multidisciplinary and overarching mechanisms of sensor morphology adaptation across biology and engineering enables us to extract relevant design principles that are important to extend our understanding of the unfinished concepts in sensing and perceptionThis study was supported by the European Commission with the RoboSoft CA (A Coordination Action for Soft Robotics, contract #619319). SGN was supported by School of Engineering seed funding (2016), Malaysia Campus, Monash University

A multirobot platform based on autonomous surface and underwater vehicles with bio-inspired neurocontrollers for long-term oil spills monitoring

This paper describes the BUSCAMOS-Oil monitoring system, which is a robotic platform consisting of an autonomous surface vessel combined with an underwater vehicle. The system has been designed for the long-term monitoring of oil spills, including the search for the spill, and transmitting information on its location, extent, direction and speed. Both vehicles are controlled by two different types of bio-inspired neural networks: a Self-Organization Direction Mapping Network for trajectory generation and a Neural Network for Avoidance Behaviour for avoiding obstacles. The systems’ resilient capabilities are provided by bio-inspired algorithms implemented in a modular software architecture and controlled by redundant devices to give the necessary robustness to operate in the difficult conditions typically found in long-term oil-spill operations. The efficacy of the vehicles’ adaptive navigation system and long-term mission capabilities are shown in the experimental results.This work was partially supported by the BUSCAMOS Project (ref. 1003211003700) under the program DN8644 COINCIDENTE of the Spanish Defense Ministry, the “Research Programme for Groups of Scientific Excellence at Region of Murcia” of the Seneca Foundation (Agency for Science and Technology of the Region of Murcia-19895/GERM/15)”, and the Spanish Government’s cDrone (ref. TIN2013-45920-R) and ViSelTR (ref. TIN2012-39279) projects

Reproducing Five Motor Behaviors in a Salamander Robot With Virtual Muscles and a Distributed CPG Controller Regulated by Drive Signals and Proprioceptive Feedback

Diverse locomotor behaviors emerge from the interactions between the spinal central pattern generator (CPG), descending brain signals and sensory feedback. Salamander motor behaviors include swimming, struggling, forward underwater stepping, and forward and backward terrestrial stepping. Electromyographic and kinematic recordings of the trunk show that each of these five behaviors is characterized by specific patterns of muscle activation and body curvature. Electrophysiological recordings in isolated spinal cords show even more diverse patterns of activity. Using numerical modeling and robotics, we explored the mechanisms through which descending brain signals and proprioceptive feedback could take advantage of the flexibility of the spinal CPG to generate different motor patterns. Adapting a previous CPG model based on abstract oscillators, we propose a model that reproduces the features of spinal cord recordings: the diversity of motor patterns, the correlation between phase lags and cycle frequencies, and the spontaneous switches between slow and fast rhythms. The five salamander behaviors were reproduced by connecting the CPG model to a mechanical simulation of the salamander with virtual muscles and local proprioceptive feedback. The main results were validated on a robot. A distributed controller was used to obtain the fast control loops necessary for implementing the virtual muscles. The distributed control is demonstrated in an experiment where the robot splits into multiple functional parts. The five salamander behaviors were emulated by regulating the CPG with two descending drives. Reproducing the kinematics of backward stepping and struggling however required stronger muscle contractions. The passive oscillations observed in the salamander's tail during forward underwater stepping could be reproduced using a third descending drive of zero to the tail oscillators. This reduced the drag on the body in our hydrodynamic simulation. We explored the effect of local proprioceptive feedback during swimming and forward terrestrial stepping. We found that feedback could replace or reduce the need for different drives in both cases. It also reduced the variability of intersegmental phase lags toward values appropriate for locomotion. Our work suggests that different motor behaviors do not require different CPG circuits: a single circuit can produce various behaviors when modulated by descending drive and sensory feedback

Investigating Sensorimotor Control in Locomotion using Robots and Mathematical Models

Locomotion is a very diverse phenomenon that results from the interactions of a body and its environment and enables a body to move from one position to another. Underlying control principles rely among others on the generation of intrinsic body movements, adaptation and synchronization of those movements with the environment, and the generation of respective reaction forces that induce locomotion. We use mathematical and physical models, namely robots, to investigate how movement patterns emerge in a specific environment, and to what extent central and peripheral mechanisms contribute to movement generation. We explore insect walking, undulatory swimming and bimodal terrestrial and aquatic locomotion. We present relevant findings that explain the prevalence of tripod gaits for fast climbing based on the outcome of an optimization procedure. We also developed new control paradigms based on local sensory pressure feedback for anguilliform swimming, which include oscillator-free and decoupled control schemes, and a new design methodology to create physical models for locomotion investigation based on a salamander-like robot. The presented work includes additional relevant contributions to robotics, specifically a new fast dynamically stable walking gait for hexapedal robots and a decentralized scheme for highly modular control of lamprey-like undulatory swimming robots

The octopus arm hydrostatic limb: an efficient link between form and function

The Octopus vulgaris arm is a remarkable example of muscular hydrostat where extraordinary motor capabilities are achieved despite the absence of a rigid skeleton. The animal eight highly flexible arms exhibit a remarkable diversity and complexity of movements and can easily adapt to the surrounding environment. Indeed, unlike structures with rigid skeletal elements, whose movements are restricted to joints, in these arms, deformations such as bending, elongation, shortening, and twisting, can occur at any location and at multiple locations simultaneously. Furthermore, the octopus can vary the stiffness of its arms, transiently converting a flexible limb into a quasi-articulated structure to accomplish complex tasks like fetching objects and walking over the sea floor. For these reasons, for over a decades the octopus has been inspiring the design of flexible robotic arms and represents nowadays an \u201canimal model\u201d for soft robotics technologies. The octopus behavior and locomotion are achieved through the combination of basic stereotyped arm motions. At the arm level, this can be obtained by the selective activation or co-activation of antagonistic muscles. The aim of this thesis is to elucidate the bases of octopus arm behavioural flexibility investigating the arm structure to function relationship. Here we show that, while having a morphologically continuous structure, the arm presents behaviourally relevant morpho-functional regionalization, especially evident at the arm apical region. An additional level of flexibility in this system is achieved through the existence of transmural strain gradients generated by a decreasing waviness of elastic fibers from outer to the inner muscle layers determining a functional higher viscoelasticity of the outer muscle layers. This might be related with the distinct functions played by muscles during motions such as accommodation of strain of the inner muscle layers and storage and release elastic energy of the outer layers. This aspect might be important for the overall arm stabilization and compliance to deformation. In support of this data, we found differences in muscle activation properties wherefore inner layers behave as slow muscles and outer layers as fast muscles. Moreover, differently from vertebrates, hydrostatic muscles can undergo large deformations thus changing dramatically the strain rate of each muscle participating in the motion. In this scenario, an activation pattern from a given motorneuron can find the same muscle in a very different strain rate during the motion. Here we found that muscle strain rate has indeed a profound influence on its mechanical work output and, in conjunction with the activation pattern and mechanism of E-C coupling, this feature might be exploited by the animal to produce a wide spectrum of arm motion. Taken together these findings support the existence of a specific arrangement of highly coordinated muscles along and within the arm bulk that is consistent with the arm use. This study is particularly relevant to further implementation in computational models able not only to simulate natural arm movements but also to predict, through a reverse engineering approach, the motion outcome of muscle ensembles. Moreover, conveying the principles governing arm flexibility might have an important impact into the design and fabrication of bio-inspired flexible robotic arms endowed with high compliance and adaptability

Hybrid bio-robotics: from the nanoscale to the macroscale

[eng] Hybrid bio-robotics is a discipline that aims at integrating biological entities with synthetic materials to incorporate features from biological systems that have been optimized through millions of years of evolution and are difficult to replicate in current robotic systems. We can find examples of this integration at the nanoscale, in the field of catalytic nano- and micromotors, which are particles able to self-propel due to catalytic reactions happening in their surface. By using enzymes, these nanomotors can achieve motion in a biocompatible manner, finding their main applications in active drug delivery. At the microscale, we can find single-cell bio-swimmers that use the motion capabilities of organisms like bacteria or spermatozoa to transport microparticles or microtubes for targeted therapeutics or bio-film removal. At the macroscale, cardiac or skeletal muscle tissue are used to power small robotic devices that can perform simple actions like crawling, swimming, or gripping, due to the contractions of the muscle cells. This dissertation covers several aspects of these kinds of devices from the nanoscale to the macro-scale, focusing on enzymatically propelled nano- and micromotors and skeletal muscle tissue bio-actuators and bio-robots. On the field of enzymatic nanomotors, there is a need for a better description of their dynamics that, consequently, might help understand their motion mechanisms. Here, we focus on several examples of nano- and micromotors that show complex dynamics and we propose different strategies to analyze their motion. We develop a theoretical framework for the particular case of enzymatic motors with exponentially decreasing speed, which break the assumptions of constant speed of current methods of analysis and need different strategies to characterize their motion. Finally, we consider the case of enzymatic nanomotors moving in complex biological matrices, such as hyaluronic acid, and we study their interactions and the effects of the catalytic reaction using dynamic light scattering, showing that nanomotors with negative surface charge and urease-powered motion present enhanced parameters of diffusion in hyaluronic acid. Moving towards muscle-based robotics, we investigate the application of 3D bioprinting for the bioengineering of skeletal muscle tissue. We demonstrate that this technique can yield well-aligned and functional muscle fibers that can be stimulated with electric pulses. Moreover, we develop and apply a novel co-axial approach to obtain thin and individual muscle fibers that resemble the bundle-like organization of native skeletal muscle tissue. We further exploit the versatility of this technique to print several types of materials in the same process and we fabricate bio-actuators based on skeletal muscle tissue with two soft posts. Due to the deflection of these cantilevers when the tissue contracts upon stimulation, we can measure the generated forces, therefore obtaining a force measurement platform that could be useful for muscle development studies or drug testing. With these applications in mind, we study the adaptability of muscle tissue after applying various exercise protocols based on different stimulation frequencies and different post stiffness, finding an increase of the force generation, especially at medium frequencies, that resembles the response of native tissue. Moreover, we adapt the force measurement platform to be used with human-derived myoblasts and we bioengineer two models of young and aged muscle tissue that could be used for drug testing purposes. As a proof of concept, we analyze the effects of a cosmetic peptide ingredient under development, focusing on the kinematics of high stimulation contractions. Finally, we present the fabrication of a muscle-based bio-robot able to swim by inertial strokes in a liquid interface and a nanocomposite-laden bio-robot that can crawl on a surface. The first bio-robot is thoroughly characterized through mechanical simulations, allowing us to optimize the skeleton, based on a serpentine or spring-like structure. Moreover, we compare the motion of symmetric and asymmetric designs, demonstrating that, although symmetric bio-robots can achieve some motion due to spontaneous symmetry breaking during its self-assembly, asymmetric bio-robots are faster and more consistent in their directionality. The nanocomposite-laden crawling bio-robot consisted of embedded piezoelectric boron nitride nanotubes that improved the differentiation of the muscle tissue due to a feedback loop of piezoelectric effect activated by the same spontaneous contractions of the tissue. We find that bio-robots with those nanocomposites achieve faster motion and stronger force outputs, demonstrating the beneficial effects in their differentiation. This research presented in this thesis contributes to the development of the field of bio-hybrid robotic devices. On enzymatically propelled nano- and micromotors, the novel theoretical framework and the results regarding the interaction of nanomotors with complex media might offer useful fundamental knowledge for future biomedical applications of these systems. The bioengineering approaches developed to fabricate murine- or human-based bio-actuators might find applications in drug screening or to model heterogeneous muscle diseases in biomedicine using the patient’s own cells. Finally, the fabrication of bio-hybrid swimmers and nanocomposite crawlers will help understand and improve the swimming motion of these devices, as well as pave the way towards the use of nanocomposite to enhance the performance of future actuators.[spa] La bio-robótica híbrida es una disciplina cuyo objetivo es la integración de entidades biológicas con materiales sintéticos para superar los desafíos existentes en el campo de la robótica blanda, incorporando características de los sistemas biológicos que han sido optimizadas durante millones de años de evolución natural y no son fáciles de reproducir artificialmente. Esta tesis cubre varios aspectos de este tipo de dispositivos desde la nanoescala a la macroescala, enfocándose en nano- y micromotores propulsados enzimáticamente y bio-actuadores y bio-robots basados en tejido muscular esquelético. En el campo de nanomotores enzimáticos, existe la necesidad de encontrar mejores modelos que puedan describir la dinámica de su movimiento para llegar a entender sus mecanismos de propulsión subyacentes. Aquí, nos enfocamos en diversos ejemplos de nano- y micromotores que muestran dinámicas de movimiento complejas y proponemos diferentes estrategias que se pueden utilizar para analizar y caracterizar este movimiento. Moviéndonos hacia robots basados en células musculares, investigamos la aplicación de la técnica de bioimpresión en 3D para la biofabricación de músculo esquelético. Demostramos que esta técnica puede producir fibras musculares funcionales y bien alineadas que puede ser estimuladas y contraerse con pulsos eléctricos. Investigamos la versatilidad de esta técnica para imprimir varios tipos de materiales en el mismo proceso y fabricamos bio-actuadores basados en músculo esquelético. Debido a los movimientos de unos postes gracias a las contracciones musculares, podemos obtener medidas de la fuerza ejercida, obteniendo una plataforma de medición de fuerzas que podría ser de utilidad para estudios sobre el desarrollo del músculo o para testeo de fármacos. Finalmente, presentamos la fabricación de un bio-robot basado en músculo esquelético capaz de nadar en la superficie de un líquido y un bio-robot con nanocompuestos incrustados que puede arrastrarse por una superficie sólida. El primer de ellos es minuciosamente caracterizado a través de simulaciones mecánicas, permitiéndonos optimizar su esqueleto, basado en una estructura tipo serpentina o muelle. El segundo bio-robot contiene nanotubos piezoeléctricos incrustados en su tejido, los cuales ayudan en la diferenciación del músculo debido a una retroalimentación basada en su efecto piezoeléctrico y activada por las contracciones espontáneas del tejido. Mostramos que estos bio-robots pueden generar un movimiento más rápido y una mayor generación de fuerza, demostrando los efectos beneficiales en la diferenciación del tejido

Biomimetic leg design and passive dynamics of Dolomedes aquaticus

Spiders provide working models for agile, efficient miniature passive-dynamic robots. Joints are extended by haemoplymph (hydraulic) pressure and flexed by muscle-tendon systems. Muscle contraction in the prosoma leads to an increase in hydraulic pressure and subsequently leg extension. Analysis of body kinematics the New Zealand fishing spider, Dolomedes aquaticus indicates that elastic plates around the joints absorb energy from the ground reaction force when the force vector points backwards (i.e. would decelerate the spider’s body in the direction of locomotion) and release it to provide forward thrust as the leg swings backwards. In addition to improving energy efficiency, this mechanism improves stability by passively absorbing energy from unpredictable foot-ground impacts during locomotion on uneven terrain. These principles guided an iterative design methodology using a combination of 3D modelling software and 3D printing techniques. I compared and contrasted compliant joints made of a variety of plastic materials. The final 3D-printed spider leg prototype has a stiff ABS exoskeleton joined by a compliant polypropylene backbone. The entire structure envelopes a soft silicone pneumatic bladder. FEA analysis was used to determine the ideal shape and behavior of the pneumatic bladder to actuate the exoskeleton. The spider leg can be flexed and contracted depending on the input pressure. To laterally actuate this pneumatic spider leg I designed and developed a fabrication system that uses vacuum injection molding to produce an integrated mesh sleeve/elastomer pneumatic actuator. I designed an apparatus to measure pressure and contraction of silicone and latex pneumatic muscles when inflated. I analyzed the non-linear pressure-contraction relationships of silicone versus latex pneumatic muscles, and also derived force-contraction relationships. From efficiency studies, both media muscles proved to be inefficient and the measuring apparatus needs to be more robust to prevent leaking air. The fabrication process still offers the possibility of a quick and efficient method of creating pneumatic muscles. A spider-like robot that implements these pneumatic muscles and pneumatic leg design could be used to explore the efficiency and stability of passive dynamic legged locomotion in spider-like robots